A hybrid vehicle which has a planetary gear train including a sun gear, a carrier and a ring gear which are capable of differentially rotating with one another is known (for example, see Patent Literatures 1 and 2). The Patent Literature 1 proposes a technology for storing a lubricating oil, which is ejected to the planetary gear train via an ejecting hole from an inside of an input shaft of an internal combustion engine, in a lubricating oil tank which is located at an inner surface of the ring gear and which is located at a position which faces a pinion gear along an axial direction, in order to supply the lubricating oil to the planetary gear train. This technology allows the lubricating oil which is stored in the lubricating oil tank to be supplied to the pinion gear via a through-hole which is formed on a wall of the lubricating oil tank by using a water head difference in the lubricating oil tank.
In addition, the Patent Literature 2 is listed as a background art which is related to the present invention. In the Patent Literature 2, a clutch for engaging and opening a connection between the carrier and the input shaft of the internal combustion engine and a brake for stopping a rotation of the carrier are additionally appended to the planetary gear train. When the clutch is in an ON state (namely, the carrier and the input shaft are engaged) and the brake is in an ON state (namely, the rotation of the carrier is stopped), the hybrid vehicle is capable of driving (for example, power-running or regenerating) by using torques of both of a rotating electrical machine which is coupled to the sun gear and a rotating electrical machine which is coupled to the ring gear.